A monolithic ceramic capacitor, which is a main application of the present invention, is generally manufactured in the following way.
First, a ceramic green sheet containing a dielectric ceramic raw material on which an electroconductive material having a desired pattern to be formed into an internal electrode is applied is prepared.
A plurality of ceramic green sheets including the ceramic green sheets on which the electroconductive material was applied are stacked and bonded by heat pressing to form a green laminate.
The green laminate is then fired to produce a sintered laminate. The laminate includes internal electrodes formed of the electroconductive material described above.
External electrodes electrically connected to particular internal electrodes are then formed on the outer surface of the laminate. For example, the external electrodes are formed by applying an electroconductive paste that contains an electroconductive metal powder and a glass frit to the outer surface of the laminate and baking the electroconductive paste. A monolithic ceramic capacitor is thus completed.
It is desirable to use inexpensive Ni as a material of the internal electrodes to reduce the manufacturing cost of the monolithic ceramic capacitor. In this case, because Ni is a base metal, the firing atmosphere must be a reducing atmosphere to prevent oxidation of Ni during the firing process of the laminate.
In order to fire the laminate in a reducing atmosphere, the dielectric ceramic material should be resistant to reduction. International Publication WO 2006/114914 (hereinafter referred to as Patent Document 1) discloses a KSr2Nb5O15 ceramic composition as a reduction resistant material having excellent electrical characteristics. This ceramic composition has a tungsten bronze crystal structure and differs completely from barium titanate having a perovskite structure.
[Patent Document 1] International Publication WO 2006/114914